Security Incidents mailing list archives
[Full-Disclosure] Re: Cisco IOS Denial of Service that affects most Cisco IOS routers- requires power cycle to recover
From: lee.e.rian () census gov
Date: Mon, 21 Jul 2003 17:54:30 -0400
The kickup to supervisor level happens when the packet is targeted directly at the router's IP address (per first Cisco advisory) or just has its TTL expire in transit past the router (per revised Cisco advisory).
Has anyone been able to verify that the problem occurs when the TTL expires "in transit"? I've been able to get packets stuck on the input queue by sending to the router's interface address, sending to <network, 0> and <network, -1> but sending to a router two hops away with a TTL of 1 just gives me an icmp ttl exceeded & nothing new stuck on the input queue. Lee Richard Johnson <rdump () river com> To: incidents () securityfocus com cc: 07/20/2003 03:20 Subject: Re: Cisco IOS Denial of Service that affects most Cisco IOS routers- AM requires power cycle to recover Please respond to rnews In article <Pine.BSO.4.53.0307172223150.11409 () rhiannon precision-guesswork com>, Tina Bird <tbird () precision-guesswork com> wrote:
information on the detailed structure of the evil packets in these protocols is not yet public AFAIK.
The router has problems if it receives a packet, content irrelevant, that makes it to supervisor level claiming an IP protocol that it doesn't have code to handle. The kickup to supervisor level happens when the packet is targeted directly at the router's IP address (per first Cisco advisory) or just has its TTL expire in transit past the router (per revised Cisco advisory). Send enough packets (default 75), and the input queue is full. hping is enough of a launch platform for that--there's no need for questionable-source exploit binaries when testing. Richard -- My mailbox. My property. My personal space. My rules. Deal with it. http://www.river.com/users/share/cluetrain/ --------------------------------------------------------------------------- ---------------------------------------------------------------------------- _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
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- [Full-Disclosure] Re: Cisco IOS Denial of Service that affects most Cisco IOS routers- requires power cycle to recover lee . e . rian (Jul 22)